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Return a fixed frequency of 1193182 Hz for the Performance Counter.

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This commit is contained in:
Rein Klazes 2005-01-19 17:01:06 +00:00 committed by Alexandre Julliard
parent c1b4d7d16f
commit 47fe880924
1 changed files with 8 additions and 5 deletions
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13
dlls/kernel/cpu.c
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@ -188,7 +188,8 @@ BOOL WINAPI QueryPerformanceCounter(PLARGE_INTEGER counter)
/* i586 optimized version */
__asm__ __volatile__ ( "rdtsc"
: "=a" (counter->u.LowPart), "=d" (counter->u.HighPart) );
counter->QuadPart = counter->QuadPart / 1000; /* see below */
/* see below */
counter->QuadPart = counter->QuadPart / ( cpuHz / 1193182 ) ;
return TRUE;
}
#endif
@ -219,10 +220,12 @@ BOOL WINAPI QueryPerformanceFrequency(PLARGE_INTEGER frequency)
{
#if defined(__i386__) && defined(__GNUC__)
if (IsProcessorFeaturePresent( PF_RDTSC_INSTRUCTION_AVAILABLE )) {
/* The way Windows calculates this value is unclear, however simply using the CPU frequency
gives a value out by approximately a thousand. That can cause some applications to crash,
so we divide here to make our number more similar to the one Windows gives */
frequency->QuadPart = cpuHz / 1000;
/* On a standard PC, Windows returns the clock frequency for the
* 8253 Programmable Interrupt Timer, which has been 1193182 Hz
* since the first IBM PC (cpuHz/4). There are applications that
* crash when the returned frequency is much higher or lower, so
* do not try to be smart */
frequency->QuadPart = 1193182;
return TRUE;
}
#endif